|Discovered by||C. H. F. Peters|
|Discovery time||September 19, 1865|
|Other names||A899 LA; A899 UA|
|Reference date March 6, 2006 (JD 2453800.5)|
|Longest distance from the Sun||473.341 Gm (3.164 AU)|
|Shortest distance from the Sun||320.334 Gm (2.141 AU)|
|Longest distance from the center of its orbital path
|396.837 Gm (2.652 AU)|
|How egg-shaped its orbit is
|How long it takes to complete an orbit||1578.081 d (4.32 a)|
|Average speed||18.12 km/s|
|Angle above the reference plane
|Longitude of where it comes up through the reference plane||203.440°|
|Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
|Size and Other Qualities|
|Average density||~1.4 g/cm³ (estimate)|
|Gravity at its surface||~0.028 m/s² (estimate)|
|Slowest speed able to escape into space
|~0.07 km/s (estimate)|
|How long it takes to turn around one time||0.2864 d (6.875 h) |
|How much light it reflects||0.067 |
|Avg. surface temp.||~172 K
max: 272K (-2° C)
85 Io is a big, dark Main belt asteroid of the C spectral class. It is probably a primitive body made of carbonates. Like 70 Panopaea it orbits within the Eunomia asteroid family but it is not related to the shattered parent body.
Io is a retrograde rotator, with its pole pointing towards one of ecliptic coordinates (β, λ) = (-45°, 105°) or (-15°, 295°) with a 10° uncertainty. This gives an axial tilt of about 125° or 115°, respectively. Its shape is quite spherical.
Other websites[change | change source]
References[change | change source]
J. Torppa et al. Shapes and rotational properties of thirty asteroids from photometric data, Icarus, Vol. 164, p. 346 (2003).
- PDS lightcurve data
A. Erikson Photometric observations and modelling of the asteroid 85 Io in conjunction with data from an occultation event during the 1995-96 apparition, Planetary and Space Science, Vol. 47, p. 327 (1999).
G. A. Krasinsky et al. Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).